package 数论;

import java.math.BigDecimal;
import java.util.Scanner;

public class 刷题统计 {
    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);
        long a = scanner.nextLong();
        long b = scanner.nextLong();
        long c = scanner.nextLong();

        long week = a * 5 + b * 2; //每周做题数

        long days = (c / week) * 7;

        long l = c % week; //剩余天数

        long count = 0;
        for (int i = 1; i <= 7; i++) {
            if (count >= l) {
                break;
            }
            days++;
            if (i == 6 || i == 7) {
                count += b;
            } else {
                count += a;
            }
        }
        System.out.println(days);
    }
}
